Harrisons has some lighter shades in a camel hair/wool blend too. But W Bill has quite an extensive collection in varying shades.
There's another lesser known Scottish weaver who weaves overcoat fabrics and I distinctly recall seeing lighter shades in camel colour. Isn't one of those large merchants, but produces very good stuff nonetheless, and there are cards of swatches at quite a number of good English tailors. Reasonably priced too. Name eludes me now, but I'll update when it comes back.